High loft, non-woven, uniform density web structures comprise a variety of everyday products. Examples may be found in products such as cleaning pads, scrubber and polishing pads, furniture batting, furnace filters, sand and dirt barriers, construction material barriers, and the like. A particular and exemplary application for such high loft, non-woven, uniform density web structures may be seen with regard to ridge vents for a gable-style roof.
It is well-known that a vent along the ridge of a gable-style roof is effective in drawing hot, stale air out of the interior space covered by the roof, usually an attic. Convection flow draws the highest temperature air to the ridge crest and out the vent. Wind across the vent line is directed up and over the vent by the sloping sides of the roof, creating a lower pressure at the vent which draws air out of the attic even when there is little convection current. When combined with soffit vents under the eaves to draw fresh air, a ridge vent usually provides more effective attic ventilation than turbine vents or large vent cans. The effectiveness of the vent depends, however, upon the degree to which convection outflow and wind across the vent line is uninhibited by the vent structure. Most effective would be a completely uncovered vent, but the need to keep out rain water, dirt, and pests requires some sort of covering structure. The design considerations for a covering structure are, therefore, to maximize convection outflow and drawn air inflow; to establish an effective barrier against water, dirt, and insect entry; and to maintain aesthetic appearance and long term durability, while providing low cost and ease of installation.
In accordance with such design considerations, a common practice for ventilating attic spaces under gable-style roofs is through use of a high loft, non-woven, uniform density fabric mat. An example of representative prior art fabric meeting this description may be seen with reference to U.S. Pat. No. 5,167,579 issued Dec. 1, 1992 to Rotter. Such fabric is made of randomly aligned fibers which are bonded with latex, acrylic, or phenolic resins. The fabric is permeable, and is most typically approximately 10½″ wide and approximately 18 mm thick. Installed, the fabric runs along most, if not all, of the uppermost ridge of the roof.
As may be seen with reference to FIG. 1 (prior art), the fabric is installed on top of an approximate 1½″ to 2″ open slot in the roof. In new construction, the slot is formed by cutting the upper row sheeting panels of the roof a predetermined amount short of the ridge crest formed by the rafters in a roof truss. In existing structures, the slot can be formed by cutting away the same size strip from the sheeting at the ridge on both sides, taking care not to damage the rafters or ridge pole, and terminating a predetermined distance from the front and back sides of the roof.
Roof shingles are laid in overlapping rows in the conventional manner up to the slot. As is well-known in the art, the fabric may easily be laid over the slot by unwinding one end of the material from a roll and centering it over the slot at one end, then unrolling it in a continuous strip to the other end, where it is cut from the roll. If it is necessary or desirable to join strips of the fabric, such joinder can be made by merely coating the abutting ends with synthetic rubber sealant used for bonding asphalt shingles and sealing around flashing, or any other suitable caulk or adhesive, and abutting the strips end-to-end, as is known in the art.
A ridge cap, formed from cap shingles, is affixed on top of the fabric in order to prevent rain water from entering the attic space through the aforedescribed permeable ridge vent fabric and open slot. Starting from one end and working to the other, each cap shingle is laid over the fabric. Each cap shingle overlaps the edge of the preceding cap shingle, and is secured by driving roofing nails through the cap shingle, fabric, and roof shingle into the underlying sheeting and rafters. The fabric is sufficiently resistant to compression that the installer can easily feel when the shingle is pressed firmly against the fabric, and can sink the nail only until the nail head is against the shingle, leaving the cap raised about ⅝″ above the underlying roof shingles.
Thus, as described, the fabric runs the length of the slot, overlapping the slot evenly on each side, and is of such low profile that it does not attract attention when covered by cap shingles or tiles of the same color and texture as used on the rest of the roof.
With the ridge cap covering only the top surface of the non-woven, high loft fabric, the linear edges, or “sides,” of the high loft fabric are exposed. This allows for hot air from inside the interior space to pass through the open slot that runs along the roof ridge line, through the bottom side of the permeable, high loft, non-woven fabric, and out through the exposed sides of the fabric.
Since the high loft, non-woven fabric and ridge cap are wider than the open slot along the ridge line, and because it is installed on a gable-style roof with the exposed ends of the fabric below the peak elevation of the middle of the fabric, the fabric provides adequate air ventilation, and also forms an effective barrier against wind driven rain, snow, insects, and debris entering the attic space.
Disadvantageously, however, the middle portion of the high loft, non-woven fabric that directly covers the open slot is not effective in preventing water and certain debris from infiltrating inside the attic space. Accordingly, the middle portion of the fabric serves primarily as a gap space to facilitate airflow. Since the area between the exposed outside end of the high loft, non-woven fabric and the inside open slot is the most critical in preventing outdoor elements, such as rain, snow, insects, and debris, from entering the interior space, it would be desirable to produce an improved, high loft, non-woven fabric, comprising a variable density web. Such an improved, high loft, non-woven, variable density web structure would provide for improved, desirable physical properties, such as higher rates of airflow and greater compression resistance, at a reduced overall total weight.
By forming a high loft, non-woven fabric with a higher concentration of fibers along the edges, and a lower concentration of fibers along the middle, a fabric can be produced at an overall lower basis weight, providing improved air ventilation properties, all while continuing to serve as an effective barrier to water, debris, and insect infiltration.
While an exemplary application for such an improved, high loft, non-woven, variable density web structure has been described above in association with ridge vents for gable-style roofs, it will be appreciated that numerous other and further applications are contemplated, including, but not limited to, cleaning pads, scrubber and polishing pads, furniture batting, furnace filters, sand and dirt barriers, construction material barriers, and the like.
Accordingly, it is to the provision of processes for creating such improved, high loft, non-woven, variable density web structures that the present disclosure is directed.